The current invention is in the field of the satellite navigational system.
In the available art relating to the satellite positional systems (SATPS), the curvature of terrain is not taken into account.
Indeed, the SATPS provides the 3-D location of signal reception (for instance, the 3-D location of the antenna). However, the position of interest is often not the same as where the satellite receiver (SR) is located since the SR is placed in the location for good signal reception. For example, for a tractor towing an implement, the best location for the SR may be on top of the tractor cab, but the position of interest (POI) for providing guidance to the tractor operator may be the position on the ground below the operator. If the tractor is on a flat terrain, determining this POI is a simple adjustment to account for the antenna height. However, if the tractor is on an inclined terrain with a variable tilt, which is often the case, the SATPS alone cannot determine the terrain tilt so the POI also cannot be determined. This results in a guidance error because the POI is approximated by the point of reception (POR), and this approximation worsens as the terrain inclination increases. By measuring tilt of vehicle with inexpensive tilt sensors, the POI can be determined, and the guidance error caused by the tilt of the terrain can be reduced.
In addition, in the prior art satellite guided parallel swathing for precision farming, the actual curvature of terrain is also not taken into account. This results in a less than precise farming because of the less than precise parallel swathing. Indeed, in order to provide parallel swaths through a field, the guidance system collects positions of the vehicle as it moves across the field. When the vehicle turns around at the end of the field and commences the next pass through the field, the guidance system sets the collected positions for the previous pass by the width of the complement (i.e. swath width). If only 3-D coordinates are collected, the next swath computations should assume a flat terrain offset. This set of next swath positions is used to provide guidance to the operator as he drives vehicle through the field. The current vehicle location as compared to the desired swath location is provided to the driver. However, if the terrain is inclined, the horizontal swath offset is in error because it does not take into consideration the curvature of the terrain. On inclined terrain, this error can be minimized by collecting vehicle tilt configuration along each current pass or the previous pass. The swath offset thus becomes a vector taking the terrain inclination into account with the assumption that from the first swath to the next one the terrain inclination does not change too much.
To meet the challenge of taking into account the actual terrain curvature, a satellite navigational system integrated with a tilt measurement system is needed. The integrated system should be capable of precise tilt measurements of the mobile unit that moves along a variable tilt track, so that the actual curvature of terrain is included in the swath vector.
To address the shortcomings of the available art, the present invention provides a satellite navigational system integrated with a tilt measurement system that is capable of precise measurement of the actual coordinates of the mobile unit that moves along a track with a variable tilt.
One aspect of the present invention is directed to a real time positioning system comprising: (1) a satellite positioning system (SATPS) receiver mounted in a housing means of a mobile unit; and (2) a tilt angle measurement device integrated with the SATPS receiver. The SATPS receiver is configured to perform three dimensional coordinates measurements of the mobile unit, and the tilt measurement device is configured to perform tilt measurements of the mobile unit.
In one embodiment, the system further comprises a SATPS/tilt integrated navigational computer configured to calculate three dimensional coordinates of an implement mounted in the mobile unit by solving a set of geometrical equations including the three dimensional coordinates of the mobile unit, the tilt coordinates of the mobile unit that are measured synchronously with the three dimensional coordinates of the mobile unit, and a distance between the SATPS receiver and the position of interest for the application.
The SATPS receiver can comprise: an RTK differential GPS receiver, a differential GPS receiver, a GLONASS receiver, or a combined GPS/GLONASS receiver. The tilt angle measurement device can comprise: an electronic tilt measurement device. The electronic tilt measurement device can comprise a single angle measurement device or a dual angle measurement device.
Another aspect of the present invention is directed to a map generating system. In one embodiment, the map generating system comprises: (1) a satellite positioning system (SATPS) receiver mounted in a housing means of a mobile unit; (2) a tilt angle measurement device integrated with the SATPS receiver; (3) a SATPS/tilt integrated navigational computer; and (4) a memory unit.
In one embodiment, the SATPS receiver is configured to perform three dimensional coordinates measurements of the mobile unit, the tilt measurement device is configured to perform tilt coordinates measurements of the mobile unit, and the SATPS/tilt integrated navigational computer is configured to calculate three dimensional coordinates of an implement mounted in the mobile unit. The memory unit is configured to record three dimensional coordinates of the implement in order to generate a map of an actual area covered by the implement.
In one embodiment of the map generating system, the (SATPS) receiver further comprises a differential GPS post-processing receiver, the mobile unit further comprises a farm tractor towing a spray unit, and the map generating system generates an xe2x80x9cas-appliedxe2x80x9d map of the area sprayed on.
Yet, one more aspect of the present invention is directed to a method of 3-dimensional line forming using a satellite navigational system integrated with a tilt measurement system. In the preferred embodiment, the method comprises the following steps: (A) defining a first 3-dimensional form line using at least two terrestrial locations; (B) defining a second 3-dimensional form line, while following the first 3-dimensional form line and deviating from the first 3-dimensional form line to accommodate one or more terrain features; and (C) updating the second 3-dimensional form line as defined in the preceding step (B).
One additional aspect of the present invention is directed to a 3-dimensional form line following apparatus. In one embodiment, the 3-dimensional form line following apparatus comprises a mobile unit further comprising: (a) a satellite navigational receiver including a satellite antenna configured to receive a set of satellite navigational data and a set of satellite navigational correction data; (b) a tilt measurement system configured to generate a set of tilt measurement data; and (c) a processor configured to compute a set of position information using the set of satellite navigational data and the set of satellite navigational correction data; and the set of tilt measurement data; and configured to define an updated 3-dimensional form line having been defined using positioning data derived from an earlier received set of satellite navigation data, from an earlier generated set of tilt measurement data, and from a swathing offset vector; and (b) deviating from the previously computed 3-dimensional form line to accommodate one or more terrain features and/or operator""s errors.